Lubricating films



United States Patent O 3,400,083 LUBRICATING FILMS Harvey J. Schugar, New York, N.Y., and Michael J.

Furey, Berkeley Heights, N.J., assignors to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Filed July 10, 1964, Ser. No. 381,898

7 Claims. (Cl. 25242.7)

The present invention is broadly concerned with a novel class of lubricity additives, additive concentrates, and oleophilic liquid compositions containing these mixtures. The invention is more specifically concerned with improving the lubricity of hydrocarbon liquids such as gasolines, aviation turbo fuel, kerosene, diesel fuel, lubracting oil and mineral lubricating oils. Other base fluids include liquid carbohydrates and esters such as dioctyl sebacate and didecyl adipate. The present invention also contemplates the use of the lubricity additives in solid products such as paraffin wax, lubricating grease and Carbowax. The invention in one specific aspect relates to improving the lubricity of middle distillates, particularly jet fuels.

Many oil compositions are designed for lubricating under boundary conditions (e.g. crankcase oils, aviation Oils and gear oils) where the prevention of wear of the metal surfaces under heavy loading is a serious problem. One common example of such heavy loading occurs in the operation of the valve lifter mechanism of gasoline engines. Here, pressures of 50,000 to 100,000 p.s.i. can occur between the valve lifter and its actuating cam, and metal wear is accordingly high.

Another objective of the present invention is to improve the lubricity of distillate fuels boiling in the range from about 50 to 750 F. Such fuels include aviation turbo-jet fuels, rocket fuel (MILR25576B), ker-osenes, diesel fuels, and heating oils. Aviation turbo-jet fuels in which the additives may be used normally boil between about 50 and about 550 F. and are used in both military and civilian aircraft. Such fuels are more fully defined by U.S. Military Specifications MIL-F-5624F, MIL-F- 2565A, MIL-F-25554A, MIL-F-25558B, and amendments thereto, and in ASTM D-1655-62T. Kerosenes and heating oils will normally have boiling ranges between about 300 and about 750 F. and are more fully described in ASTM Specification D-396-48T and supplements thereto, where they are referred to as No. 1, and No. 2 fuel oils. Diesel fuels in which the additivesbe may employed are described in detail in ASTM Specification D-975-35T and later versions of the same specification. These additives maybe used in metal working fluids in machining. 1

The additives of the present invention may also be employed in conjunction with a variety of other additives commonly used in fuels such as those set forth above. Typical of such additives .are rust inhibitors, anti-emulsifying agents, corrosion inhibitors, anti-oxidants, dispersants, dyes, dye stabilizers, haze inhibitor, antistatic agents and the like. It will frequently be found convenient to prepare additive concentrates for use in the various types of fuels and thus add all of theadditives simultaneously.

Broadly, the additives of the present invention may be classified as:

(I) Mixtures of compounds X and Y in a carrier fluid, and v (H) Reaction products of X and Y in a carrier fluid.

Where:

X=M(OR) -and Y=an organic polyol or polyamine, and

where:

1 Eg. machining and lubrication of steel and ferrous alloys, aluminum alloys, titanium, brass, stainless steel, etc.

M=Ti or other transition elements such as Hf, Ce, V, Nb, Fe and V; a Group IV element such as Si, Ge, Sn or Pb; B or Al (Group III elements); or a Group V element such as P, As, Sb or Bi.

R=a monovalent alkyl group containing from 1 to 12 and preferably from 1 to 6 carbon atoms (e.g. CH 2 5 3 '1, o 13) n=2 or greater, depending upon the valence of M, and

preferably 3 or 4.

It is preferred that M=Ti, Si, B and P. Y=a polyol (eg a glycol, HO-R'OH) or a polyamine (e.g. a diamine, H NRNH where R is an organic radical containing 8 to 40, and preferably 20 to 36, carbon atoms.

Specific examples of M(OR) are Ti(OC H tetraethyl orthotitanate; Ti(OC H tetrabutyl orthotitanate; Si(OC H tetraethyl orthosilicate; Si(OC H tetrahexyl orthosilicate; B(OC H tributyl borate; B(OC H trioctyl borate; P(OC H triethyl phosphite; and P(OC 'H tributyl phosphite.

It is recognized that some alkoxides are monomer only under special conditions (e.g. very dilute solution). For example, Ti(OC H Ti(OC H and Ti(OC H are trimeric, Ti (OR) Consequently, it is understood that M (OR) in this invention may be replaced by (M(OR),,) where x is greater than 1.

Specific examples of polyols are, for example, ethylene glycol; 1,4-butane diol; 1,5-pentane diol; 1,2,6-hexane triol; C glycol made from C dilinoleic acid; C glycol made by reacting ethylene glycol and C dilinoleic acid; esters of sorbitol and fatty acids and which still contain two or more hydroxy groups (eg sorbitan monooleate); polypropylene glycol; 1,4-cyclohexane dimethanol; and C glycol made by the aldolization of iso-octyl aldehyde.

Specific polyamines are, for example, triethylene tetramine; tetraethylene pentamine; dimer triamine, dimer diamine and dimer tetramine made from C dilinoleic acid; imino-bis-propyl amine; 1,6-hexane diamine; and pphenylene diamine.

In place of polyols or polyamines, compounds having both a hydroxy group (OH) and an amine group N-H may be used. Examples of these compounds are alkanolamines such as monoethanolamine, N-aminoethyl ethanolamine and polyglycolamines (e.g.

The specific structures chosen for compounds X and Y will depend, among other things, on the carrier fluid to be used and whether or not a solutionrather than collodial dispersionof the compound(s) is desired. For example, if a hydrocarbon such as kerosene or mineral oil is to be used as the carrier fluid and if solubility is desired, then the preferred polyols and polyamines would be the C to C compounds derived from C dilinoleic-acid. Secondly, if one of the compounds (either X or Y) is of borderline or poor solubility in the carrier fluid, X and Y may be partially reacted first before addition to the carrier. Furthermore, the reaction product of X and Y is frequently more effective than the mixture of X and Y in reducing wear and scufiing. It is believed that this is due to the fact that when only one species is involved, adsorbed layers contain equal amounts of the X and Y structural features, each of which is important. On the other hand, with a mixture, one compound may be so poorly or weakly adsorbed on a surface (e.g. metal) that it does not take part in the protection of the surface.

The reaction products may be prepared as follows:

In order to further illustrate ing examples are given:

TABLE II Percent metallic contact Coefi. of friction 2 Additives in mineral oil 1 240 g. 1,000 g. 4,000 g. 240 g. 1,000 g. 4,000 g.

None 85 93 99 0. 103 0. 093 0. 085 1% tetraethyl-o-silicate/ethylene glycol product 9 1 2 0. 071 0. 046 0. 062 1% tetraethyl-o-silicate 6 31 100 0. 109 0.101 0.105 1% tetraethyl-o-silicate/sorbitan monooleate reaction product 74 82 99 0. 090 0. 065 0. 078

1 Paraflinic distillate oil: Vis. Saybolt sec. 100 at 100 F.; vis. index 90-110; boiling range 050 F. to 800 F 2 Ball-on-eylinder tests, steel-on-steel (AISI 52100) 240 r.p.m., 32 minutes. The apparatus used is described in the Journal of the American Society of Lubrication Engineers, entitled ASLE Transactions, vol. 4, pages 1-11 in 1961. ASLE is American Society of Lubrication Engineers. In essence, the system consists basically of a fixed metal ball loaded against a rotating cylinder. The extent oi metallic contact is determined by measuring both the instantaneous and average electrical resistance between two surfaces. The apparatus is described in U.S. Patent 3,129,580 issued May 21, 1964, entitled "Apparatus for Measuring Friction and Contacts Between Sliding Lubricating Surfaces; Inventors: Furey et al.

Table II shows that the tetraethyl-o-silicate/ethylene glycol monoester is extremely effective in reducing metallic contact over the entire load range. It is also effective the invention, the follow- EXAMPLE 1 Table I summarizes the results of ball-on-cylinder tests using combinations of tetraethyl-orthosilicate, (EtO) Si,

as an antifriction additive. A similar monoester made with sorbitan monooleate as the polyol, however, is much less effective. This suggests that lower molecular weight and dimer tetramine and dimer diamine. These are not l c l or polyols are preferred.

reaction products but simply mixtures.

TABLE I Percent metallic contact 2 Coefi. of friction 1 Additives in mineral oil l 240 g. 1,000 g. 4,000 g. 240 g. 1,000 g. 4,000 g.

No lylet.... i:i1. 1. .1 6 85 93 99 0.103 0.093 0.085 0.5 etrae y -o-si ica e 5 dimer tetrammm 0 0 0 0. 055 0. 066 0.085 1% tetraethyl-o-silicate. 6 31 100 0. 109 0. 101 0. 105 3% 7difier tfizlralminfiiui 1 12 99 0. 043 0. 063 0. 080

.5 e rae y -o-s ea e g dimer dime 12 7 100 0. 117 o. 091 o. 089

l Parafiinic distillate oil; Vis. Saybolt sec. 100 at 100 F.; vis. index 90-110; boiling range 650 F. to 800 F.

2 Ball-on-cylinder tests, steel-on-steel (AISI 52100), 240 r.p.m., 32 minutes, 77 F. oil temperature. The apparatus used is described in the Journal of the American Society of Lubrication Engineers, entitled ASLE Transactions, vol. 4, pages 1-11 in 1961. ASLE is American Society of Lubrication Engineers. In essence, the system consists basically of a fixed metal ball loaded against a rotating cylinder. The extent of metallic contact is determined by measuring both the instantaneous and average electrical resistance between two surfaces. The apparatus is described in US. Patent 3,129,580 issued May 21, 1964 entitled Apparatus for Measuring Friction and Contacts Between Sliding Lubricating Surfaces; Inventors; Furey et al.

It can be seen from Table I that a combination of (EtO) Si and dimer tetramine is extremely effective in reducing metallic contact at all loads triedeven at 4000 g. (141,000 p.s.i. mean Hertz pressure). Metallic contact is reduced to zero. This is even better than the metal dithiophosphates which tend to act only at the higher load. Neither tetraethyl-o-silicate nor the tetramine alone at the same total concentration (1 Wt. percent) has any effect at the highest load (4000 g.). They do, however, show some benefits at lower loadsand the tetramine alone reduces friction. However, only the combination produces low metallic contact as well as low friction over the entire load range.

Table I also shows that the tetramine combination is much preferred over combinations with either dimer diamine.

EXAMPLE2 In another approach, tetraethyl-o-silicate was reacted with ethylene glycol to form a monoester as described. 0.2 mole (41.6 g.) of the silicate and 0.2 mole (12.4) of ethylene glycol were placed in a 250 1111., 2 neck flask containing boiling chips and a magnetic stirrer and a side arm to collect ethanol. A few crystals of p-toluene EXAMPLE 3 Preparation of (RO) B/polyol monoesters 1 A. Triethyl borate-l-ethylene glycol. 0.1 mole (EtO) B (15.6 g.)+0.1 mole ethylene glycol (6.2 g.) was heated in flask with no solvent until theoretical (0.1 mole) ethanol was collected. .The reaction took 15 minutes at 0., resulting in a clear, water-white fluid. 1% in mineral oil produces a hazy blend. 1

B. Triethyl borate+sorbitan monooleate-0.1 mole (EtO) B (15.6 g.)+0.1 mole sorbitan monooleate was heated in flask with no solvent until 6 ml. ethanol collected (theoretical amount is 5.3'ml.). Refluxing occurred when the liquid temperature reached to C. and the condensate temperature was 80 to 85 C. The product was a clear, yellow liquid with fairly good solubility in mineral oil. The results are shown in Table III.

TAB LE III Percent metallic contact 2 Coefi. of friction 1 Additives in mineral oil 1 240 g. 1,000 g. 4,000 g. 240 g. 1,000 g. 4,000 g.

None 85 93 99 0. 103 0. 093 0. 085 1% triethyl borate/ethylene glycol product 1 11 0. 029 0. 055 0.066 1% triethyl borate/sorbitan monooleate product 0 3 70 O. 087 0. 079 0. 082 1% triethyl borate 0' 6 33 0. 120 0. 116 0. 117

1 Paraflinic distillate oil: Vis. Saybolt sec. 100 at 100 F; Vis. index 90-110; boiling range 650 F. to 800 F. Z Ball-on-cylmder tests. steel-on-steel (AISI 52100), 240 r.p.m., 32 minutes. The apparatus used is described 111 the Journal of the American Society of Lubrication Engineers, entitled ASLE Transactions, vol. 4, pages 1-11 m 1961. ASLE is American Society of Lubrication Engineers. In essence, the system consists basically of a fixed metal ball loaded against a rotating cylinder. The extent of metallic contact is determined by measuring both the instantaneous and average electrical resistance between two surfaces. The apparatus is described in U.S. Patent 3,129,580 issued May 21. 1964, entitled, Apparatus for Measuring Friction and Contacts Between Sliding Lubricating Surfaces; inventors: Furcy et a1.

As can be seen from the data in Table III, the ethylene glycol derivative is quite effective in reducing metallic contact and also surprisingly potent in reducing friction by a substantial amount over the entire load range. The sorbitan monooleate derivative is much less effective and actually produces more metallic contact at the high load (4000 g.) than triethyl borate alone. The borate by itself reduces metallic contact but not friction. However, it is not nearly as effective as the borate/ glycol monoester.

The two products prepared show some haze in mineral oil at 1% concentration. Trialkyl borates having a larger number of carbon atoms (e.g., from 3 to 8 carbon atoms) as the alkyl group would eliminate the haze and also produce materials of greater hydrolytic stability.

EXAMPLE 4 A. 0.1 mole tributyl phosphite (25.0 g.) and 0.1 mole C dimer diamine (53.1 g.) was heated with stirring in flask with no solvent and in a N atmosphere. Heated to 110 C. for 1 hour, .theproduct was a clear, yellow fluid.

B. Prepared as above but heated to 200 C. for 1 hour collecting 3.9 m1. water-white fluid condensate (predominantly butanol) in the trap. The product was a clear, yellow, viscous fluid.

As seen by the-data in the following Table IV, these reaction products are extremely effective in reducing metallic contact, and therefore wear, even at very high loads. Although the phosphite alone has some benefit, it is not nearly as effective as the phosphite/diamine products.

TABLE IV.EFFECT 0F PHOSPHITE/DIAMINE REAC- TIQN PRODUCTS ON METALLIC CONTACT Additives in base Percent metallic oil: contact None 100 0.5% reaction product A (tributyl phosphite/ dimer diamine) 8 0.5% reaction product B (tributyl phosphite/ dimer diamine) 4 0.5% tributyl phosphite 55 0.5% dimer diamine 98 1% reaction product B 1 1% tributyl phosphite 16 1% dimer diamine 92 Ball-on-cylinder tests with stecl-on-steel (AISI 52100) at 240 r.p.m., 4 kg. load (141,000 p.s.i. mean Hertz pressure) and 32 minutes.

77"iliarnflinic mineral oil having a viscosity of 35 cp. at

EXAMPLE C. 0.1 mole tetrabutyl titanate (34 g.) and 0.1 mole dimer diamine were placed, in a flask and heated with stirring to 100 C. for 1 hour. The product was a clear, amber fluid.

D. Prepared as above except reaction temperature was increased to 200 C. and 1.0 ml. clear liquid (mostly butanol) collected in the trap. The product was a clear, amber fluid, slightly more viscous than C above. The results are shown in Table V.

TABLE V.-EFFECT OF TITANATE/DIAMINE MIXTURE AND REACTION PRODUCTS ON METALLIC CONTACT AND FRICTION 1 1 Ball-0n-cylinder tests, steel-on-steel, 1 kg. load, 240 r.p.m., 32 minutes.

'- Paraifinic mineral oil having a viscosity of 35 cp. at 77 F.

Glycol made by reacting 2 moles ethylene glycol with 1 mole Can dimer acid.

It can be seen that molar mixtures of tetrabutyl titanate with either C dimer diamine or a C glycol derived from dimer acid are effective in reducing both metallic contact and friction. In addition, the reaction products (TBT/diamine) are even more effective. (TBT alone hydrolyzes and forms insoluble material; dimer diamine alone has little effect.)

The compounds of the present invention may be used in any fluid carrier (e.g. hydrocarbons, esters, silicones, polyphenyl ethers, polyalkylene glycols, etc.) at any concentration (e.g. 0.01 to preferably 0.1 to 2) not only for lubrication (reduction of wear, scuffing, friction) but for the machining and working of metals, including titanium and its alloys, aluminum, brass and stainless steel. These compounds may also be used as lubricating fluids for non-metals (e.g. glass, plastics) and the like.

Thus the preferred lubricity additive mixtures of the present invention comprise a compound selected from the class consisting of polyols and polyamines used in a mixture with a compound selected from the class consisting of borates, silicates, phosphites and titanates. The invention is particularly concerned with a novel class of lubricity additive mixtures which are specifically adapted for use in conjunction with oleophilic liquids such as hydrocarbon lubricants and jet fuels. In accordance with the specific adaptation of the present invention, middle distillate compositions such as jet fuels are improved with respect to their lubricity by incorporating therein an effective amount of a mixture of a diol used with a compound selected from the class consisting of borates, silicates and phosphites.

The polyols of the present invention are those which may contain from about 2 up to about 50 carbon atoms. A satisfactory glycol has 16 carbon atoms and the general formula:

wherein the C and 0, alkyl groups are branched. This material was prepared by aldolization of iso-octyl aldehyde, followed by hydrogenation. The iso-octyl aldehyde that was used, was an isomeric mixture of branched chain the first stage of the well-known Oxo process. Here a C monoolefin (prepared from butylene and propylene feed) is reacted with hydrogen and'carbon'monoxideunder pressures of 1000 to 3000 p.s.i. and temperatures of about 300 to 400 F. in the presence of a cobalt carbonyl catalyst to form iso-octyl aldehyde.

Other diols are useful for the present invention. For instance, a dihydroxy compound can be prepared by esterifying one mole of dimer acid with two moles of a glycol, thus:

wherein R is the radical of a glycol and R is the hydrocarbon part of the dimer acid. The diol represented by the above formula is suitable to be used with dimer acid according to the present invention. Other suitable diols are oxa alkane diols obtained for example by hydrolysis of ethylene oxide, propylene oxide or other epoxy compounds. These diols may have molecular weights between 200 and 2000. An example is 3,6,9-trioxa-1,4,7,10-tetramethyl undecane-1,11-diol.

The preferred glycols which give excellent results are those containing from about 2 to 5 carbon atoms, for example ethylene glycol and 1,4-butane diol. Specific polyhydroxic compounds that are very desirable are for example ethylene glycol.

In place of the polyols, oil-soluble polyamines may be used such as diamines having the general formula wherein R is an alkyl radical of to 40 carbon atoms, e.g. 1,12-dodecyl diamine and 1,9-heptadecyl diamine.

The oil compositions with which the preferred mixtures are used comprise a major proportion of a hydrocarbon oil and about 0.01 to 2.0%, preferably 0.1 to 1.0 weight percent of the additive mixture of the invention. However, the concentration may be considerably higher as for example up to about by weight.

Although monomeric reaction products as shown above are preferred, it is to be understood that lower molecular weight polymeric products can also be used if they are soluble or dispersible enough in the carrier medium.

For example:

LR J.

Llm .L

n is preferably equal to 1 but may equal 1, 2, 3 or 4.

What is claimed is: '1. An improved hydrocarbon composition compris ng a major proportion of a middle distillate boiling in the 'range between about '50 and 750 F. and from about 0.01 to 1.0% by weight of an additive composition selected from the group consisting of mixtures of P(OR) and polyamines; of Si(OR) and polyols; of Si(OR) and polyamines; of B(OR) and polyols and of Ti(OR) and polyamines and reaction products of each of said mixtures; wherein R represents a monovalent alkyl group containing from 1 to 12 carbon atoms; wherein n corresponds to the valence of the first recited element of each formula and wherein said polyamine and polyol contain between about 2 and about carbon atoms.

2. The composition of claim 1 wherein said additive composition consists essentially of a mixture of alkyl phosphites and polyamines and reaction products thereof.

3. Improved hydrocarbon composition consisting essentially of a middle distillate boiling in the range from about 50 to 750 F. and containing from about 0.01 to 1.0% by Weight of a mixture consisting of tetraethyl orthosilicate and C dimer tetramine.

4. Improved hydrocarbon composition consisting essentially of a middle distillate boiling in the range from about 50 to 750 F. and containingfrom about 0.01 to 1.0% by weight of a reaction product of tetraethyl-o-silicate and ethylene glycol.

5. Improved hydrocarbon composition consisting essentially of a middle distillate boiling in the range from about 50 to 750 F. and containing from about 0.01 to 1.0% by weight of a reaction product of triethyl borate and ethylene glycol.

6. Improved hydrocarbon composition consisting essentially of a middle distillate boiling in the range from about 50 to 750 F. and containing from about 0.01 to 1.0% by weight of a reaction product of tributyl phosphite and C dimer diamine.

7. Improved hydrocarbon composition consisting essentially of a middle distillate boiling in the range from about 50 to 750 F. and containing from about 0.01 to 1.0% by weight of a mixture of tetrabutyl titanate and C dimer diamine.

References Cited UNITED STATES PATENTS 2,241,243 5/1941 Conary et al. 25249.8 X 2,717,242 9/ 1955' Foehr 25249.6 3,125,525 3/1964 Siegart et al. 25249.6 X 2,485,341 10/ 1949 Wasson et al 25249.8 2,960,469 11/ 1960 Young 25242.7 3,281,358 10/1966 Furey 25251.5 XR

DANIEL E. WYMAN, Primary Examiner.

W. H. CANNON, Assistant Examiner. 

1. AN IMPROVED HYDROCARBON COMPOSITION COMPRISING A MAJOR PROPORTION OF A MIDDLE DISTILLATE BOILING IN THE RANGE BETWEEN ABOUT 50* AND 750*F. AND FROM ABOUT 0.01 TO 1.0% BY WEIGHT OF AN ADDITIVE COMPOSITION SELECTED FROM THE GROUP CONSISTING OF MIXTURES OF P(OR)N AND POLYAMINES; OF SI(OR)N AND POLYOLS; OF SI(OR)N AND POLYAMINES; OF B(OR)N AND POLYOLS AND OF TI(OR)N AND POLYAMINES AND REACTION PRODUCTS OF EACH OF SAID MIXTURES; WHEREIN R REPRESENTS A MONOVALENT ALKYL GROUP CONTAINING FROM 1 TO 12 CARBON ATOMS; WHEREIN N CORRESPONDS TO THE VALENCE OF THE FIRST RECITED ELEMENT OF EACH FORMULA AND WHEREIN SAID POLYAMINE AND POLYOL CONTAIN BETWEEN ABOUT 2 AND ABOUT 50 CARBON ATOMS. 